Aromatic polyimide (PI) and aromatic polybenzoxazole (PBO) are representative polymers having a rigid aromatic backbone, excellent mechanical strength, chemical resistance, weather resistance, heat resistance, and shape stability based on cyclic chemical stability and excellent electric characteristics such as insulation characteristic and the like due to a low dielectric constant. Thus, aromatic polyimides and aromatic polybenzoxazoles are actively used as an electric/electronic material in devices such as a display, a memory, a solar cell, and the like and also have attracted attention as a material for use in automotive and aerospace fields.
In particular, a positive photosensitive resin composition including the polybenzoxazole has recently been increasingy used in a display area as an organic insulation layer or a barrier rib material and extensively used for a laptop computer, a monitor, and a TV image due to lightness, thinness, low price, and low power consumption of a display, excellent adherence to an integrated circuit, and the like. However, the polybenzoxazole precursor (PBO) is not partially ring-closed but thermally decomposed during thermal curing and thus, deteriorates strength of a final film, chemical and heat resistance, and the like. In addition, the non-ring closed polybenzoxazole precursor may cause out gas. Thus there has been an ongoing effort to improve heat and chemical resistance, strength, dimensional stability, and the like by introducing a thermosetting cross-linking agent having an appropriate structure.